This invention pertains to improvements to machines for packaging powdered products into valve bags.
Bags of this sort equipped with valves are generally placed flat in verticle or horizontal piles.
For automatic packaging of powdered products, it is usually necessary to open the valve of the bag located at the top of the pile, hold said bag and move it, with the valve open, from the storage area where the pile is located to a filling and weighing station comprising a distributor tube over which said valve must be placed.
Up to now, these operations were performed by applying, during their entire duration, a suction to the top of the first bag on the pile, using suction cups.
Experience has shown, however, that a certain percentage of valves did not open or opened incompletely, and that these bags were dropped, so that the operation of the packaging installation was defective.
It has been noted that this sometimes high percentage of failures was due in large measure to the shocks created in the bag-handling head by insufficient sophisticated design of the pneumatic control circuits and by inertia effects in the moving parts constituting the bag-grasping head subassembly.